Purification of alkyl phenols



?atentedi done 12, 1945 sits estates CATKGN F ALKYL PHENOLS Daniel E.Luten, din, andflldo Be Eenediotis,

Berkeley, ilalii, assignors to Shell Envelopment Company, Sanlirancisco,Caliik, a corporation of Delaware No Drawing. Application reel-sa 1,less, Serial No. states 4 ll! Claims. (Cl. Edit-452?) This inventionrelates to'the pwification oiv alkyl phenols by removing nitrogencompounds from them by a solvent extraction process, and is acontinuation-in-part of our co-pending application Serial No. 354,398,filed August 27, 1940.

The term alkyl phenols, as used herein, refers to mixtures ofacid-reacting hydroxy aromatic compounds consisting predominantly ofalkyl phenols, such as may be obtained by extracting cracked mineraloils or coal tar distillates with strong aqueous caustic alkalisolutions. These mixtures usually contain nitrogen compounds of be usedto eifect this release, provided these other a composition notdefinitely known but apparently comprising lactams, at least a portionof which have slight if any basic properties and which cannottherefore'be removed by washing the alkyl phenols with solutions ofstrong acids. Neither can these nitrogen compounds be removed by washinga solution of the phenols inaqueous caustic alkali with awaterdmmiscible solvent, such as a hydrocarbon liquid; In addition,alkyl phenol mixtures ordinarily also contain small quantities of basicnitrogen compounds which can more or less readily be removed by acidtreatment. I

Alkyl phenols have a number of important applications, such as in theflotation of ores,

manufacture of resins, cyclic alcohols, ketones and the like; or asanti-oxidants, disinfectants,

selective solvents, etc. The presence of impurities such as nitrogencompounds frequently impairs the usefulness of the alkyl phenols forthese purposes.

It is therefore the object of this invention to remove from alkylphenols nitrogen compounds compounds react with the alkyl phenols toform anotherv more stable complex which displaces the non-basiccompounds from their complex with the alkyl phenols. In this way thenonbasic nitrogen compounds are released and become water-soluble sothat they may be easily removed.

The non-basic nitrogen compounds appear to be of the lactam type and wehave found that compounds other than nitrogen bases may also compoundsform complexes which are more stable than those formed by ordinaryrelatively simple lactams. Lactams, being amides, are known to formcomplexes with alkyl phenols. (See: Kremann and Wenzlng, lvlonatsheftefiir Chemie, 38, 480 (1917).)

Among the compounds known to form such complexes are nitrogen bases andthe lower fatty acids or alkanoic acids, hereinafter referred to asagents. Preferably these compounds contain from one to four carbon atomsper molecule. Some specific agents are formic, acetic, propionic,

' butyric, etc., acids. Thus,it has been found that the addition ofthese agents is capable of extracting considerable portions of non-basicnitrogen compounds not removable by strong mineral acids.

In order to facilitate this treatment, a diluent is ordinarily added tothe alkyl phenol mixture to be treated for the purpose of rendering itless viscous, thus helping phase separation. The diluent used for thispurpose may be any substantially neutral, non viscous solvent for alkylphenols which has a boiling temperature suficiently different from thealkyl phenols to permit its separation by fractional distillation andwhich does not react with the complex-forming agent or with the alkylphenols under, the conditions of 'Our co-pending application Serial No.354,398

covers a. process for removing these non-basic nitrogen compounds fromalkyl phenols by adding a basic nitrogen compound which causes thenon-basic nitrogen compounds to become soluble in water so that they maybe removed by water and/ or acid washing. These added basic nitrogen thetreatment. Preferably the diluent comprises one having a preferentialsolvent power for alkyl phenols, such as others of 48 carbon atoms, e.g. diethyl ether, di-isopropyl ether, dioxane, etc.; ketones as acetone,methyl ethyl ketone, methyl propyl ketone, diethyl ketone, ethyl propylketone, etc. However, other solvents capable of dissolving the allsylphenols may be used, such as light hydrocarbon liquids, e. g. lightgasoline, pentanes,

hexane-s, heptanes, octanes, benzene, toluene, xylenes; or oxygenatedhydrocarbons such as simple alcohols of 3 or more carbon atoms; orchlorinated hydrocarbons such as dichlorethane, chlorpropane, carbontetrachloride, 'hexachlorethane and the like. Suitable amounts ofdiluent may vary from about 25 to 500 volume percent.

In carrying out the present invention an amount of complex-formingagents at least sumcient to displace the non-basic nitrogen compoundsfrom their complexes with the allqrl phenols is admixed with the alkylphenols or their solution in a diluent. The resulting mixture is thencontacted with an amount oi water sufilcient to form two layers, analkyl phenol layer contain ing the agent and an aqueous layer containingthe non-basic nitrogen compounds and a portion or the agent. Theselayers are then separated.

The amount of agent used to carry out the treatment may convenientlyrange from about 50 to 500 mol oi the alkyl phenols, and the amount ofwater should be at least sufiicient to dissolve a substantial portion ofthe released non-basic nitrogen compounds. In general, the larger theamount water, the more non-basic nitrogen compounds are. removed. Onlyeconomical considerations impose an upper limit on these amounts. Thus,excessive quantities "of water are expensive to handle and may causelosses of alkyl phenols.

The separated alkyl phenol layer may further be contacted withquantities of more agents and water under conditions to form two layerswhich are separated; or else this layer may, if desired, merely bewashed with water once or several times to remove as much as possible ofthe non-basic nitrogen compounds.

In order to reduce possible losses of alkyl phenols by dissolution inthe wash water, an inorganic salt such as sodium chloride, sodiumsulfate, calcium chloride, etc., may be dissolved in it in amounts justsumcient to salt out the alkyl phenols.

Any convenient method for effecting the washing may be employed. Thus,ordinary mixing and settling in one or several stages may be used; orthe liquids may be contacted in a countercurrent column which, ifdesired, may embody the backwash principle. etc.

The removal of the complex-forming agents from the purified alkyl phenollayer may be achieved in several ways which depend upon the propertiesof these compounds themselves. Usually, water-washing will remove asuflicient portion. However, if desired, distillation with steam may beemployed, particularly in cases where they have relatively low boilingtemperatures substantially below the boiling temperatures of the alkylphenols, or when using salts for complex formation the alkyl phenols maybe taken overhead.

The nitrogen bases originally associated with the alkyl phenols maysimultaneously be removed with the complex-forming agent,,thus.contamigen compounds, and frequentlyin. addition varyi'ng amounts ofnitrogen bases, as well as ilkyl phenols, may be further treated indifferent ways, depending upon their exact compositions. Frequently,they are merely discarded; or else they may be subiected to fractionaldistillation, neutralization, acidification, or other conventional meansnormally employed to separate mixtures of difierent components havingdiflerent properties.

Example An alkyl phenol mixture was obtained by exnating said agent. I!for some reason this should be undesirable the alkyl phenol mixture maybe given a wash with an aqueous solution of strong mineral acid prior tothe treatment of this invention. In this manner the nitrogen basesnaturally associated with the alkyl phenols are pre-removed.

While the nitrogen bases naturally contained in the alkyl phenols helpdisplace the non-basic nitrogen compounds from their complexes, the

tion, and springing it with carbon dioxide.

strong caustic soda, steaming the resultant solu- A high boilingfraction 0! alkyl phenols so obtained contained 1.95% by weightnitrogen. 100 grams of this material were dissolved in 208 cc. ofdiisopropyl ether, and the resultant solution was extracted with 20000.of acetic acid dissolved in 500 cc. of water whereby two liquid phasesare formed, an allwl phenol phase and an aqueous phase, each containingdissolved part of the acetic acid. The two phases thus produced wereseparated, and analyzed for their nitrogen content.

The lower aqueous phase contained 1.12 grams of nitrogen and the upperphase contained .83 gram of nitrogen. This represents a reduction of thenitrogencontent of alkyl phenols from 1.95 to .83 by a single-stageextraction (which is comparable to the results shown in our co-pendingapplication Serial No. 354,398 mentioned above).

We claimasourinvention:

1. In a process for purifying alkyl phenols contaming non -basicnitrogen compounds naturally associated with petroleum and coal taralkyl phenols, which compounds are not removable from said alkyl phenolsby strong mineral acid washes, the steps comprising contacting saidallwl phenols'with at least 50 mol percent or an alkanoic acid havingfrom one to four carbon atoms and with water to produce two liquidlayers, one an alkyl phenol layer and the other an aqueouslayercontaining said non-basic nitrogen compounds, and separating saidlayers.

2. The process of claim 1 wherein said alkanoic acid has a boilingtemperature lower than the boiling temperature 01' the alkyl phenols.

3. The process of claim 1 wherein the amount of said alkanoic acid isfrom 50 to 500 mol percent of the alkyl phenols.

4. The process or claim 1 wherein said alkanoic acid is acetic acid.

5. The process or claim 1 wherein said water contains an inorganic saltto salt out dissolved alkyl phenols.

6. In the process of purifying alkyl phenols containing non-basicnitrogen compounds naturally associated with petroleum and coal taralkyl phenols, which compounds are not removable from said alkyl phenolsby strong mineral acid washes, the steps comprising contacting saidalkyl phenols with water in the presence of an alkanoic acid having rromone to tour carbon atoms, said alkanoic acid being dissolved in saidalkyl phenols and being present in an anountat least 50 mol percent ofsaid alhi phenols, whereby two liquid layers are formed, an alkyl phenollayer containing at least a substantial portion 01' said alkanoic acid,and an aqueous layer containing at least a portion or said non-basicnitrogen compounds, separating the layers, and removing the alkanoicacid from the alkyl phenol layer.

7. Intheprocessorpurityingalkylphenolsconasvaasa taining non-basicnitrogen commands naturally associated with petroleum and coal tar alkylphenols, which compounds are not removable from said alkyl phenols bystrong mineral acid washes,

the improvement comprising contacting said alkyl' phenols with water inthe presence of a neutral solvent for said alkyl phenols, inert towardsthe conditions of 'the process, and of an alkanoic acid having from oneto tour carbon atoms, said alkanoic acid being dissolved in said alkylphenols and being present in an amount at least 50 mol percent of'saidalklyl phenols, whereby two liquid layers are formed, an alkyl phenollayer containingat least a substantial p tion of said alkanoic acid andsaid solvent, and an aqueous layer containing at least a portion of saidnon-basic nitrogen compounds, separating the layers, and removing saiddissolved alkanoic acid and solvent from the alkyl phenol layer.

8. The process of claim 7 wherein the solvent isan ether.

v 9. The processoi claim 7 wherein the amount 10 of said solvent is from25% to 500% by volume of mm B. LU'I'EN, JR. ALDO DE BENEDICTIS.

said alkyl phenols.

